body,
pre {
  margin:0;
  border:0;
  word-wrap:normal;
}

pre {
  padding:5px;
  counter-reset: lines;
}

pre .line {
  counter-increment: lines;
}

pre .line::before {
  content: counter(lines);
  text-align: right;
  display: inline-block;
  width: 2em;
  padding-right: 0.5em;
  margin-right: 0.5em;
  color: #BBB;
  border-right: solid 2px;
}